Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid w...Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.展开更多
基金This work was financially supported by the National Basic Research Program of China(2019YFC1906900)Chinese Central Public Welfare Research Project(2019YSKY-016).
文摘Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.
